Question 165·Hard·Inferences
During a seven-year field experiment on alpine meadows, ecologist Marisol Chen excluded all pollinating insects from a series of fenced plots while leaving nearby control plots undisturbed. In the first three years, plants in the exclusion plots produced about 40 percent fewer viable seeds than those in the control plots, but by year 7 seed production in the exclusion plots had rebounded to equal that of the controls. Chen attributed this recovery to the marked increase, within the exclusion plots, of flowering species capable of fertilizing their own ovules without insect visitation, while insect-dependent species sharply declined. From these observations, Chen most likely inferred that, over time, a pollinator-poor environment will tend to favor plant species that _____
Which choice most logically completes the text?
For "complete the text" inference questions, first restate in your own words what the researcher observed and what explanation they gave (look for phrases like "attributed this to" or "concluded that"). Turn that specific explanation into a general rule, then scan the choices and eliminate any that introduce new ideas not in the passage, contradict the described trend, or focus on details (like timing or attracting insects) that the author never mentioned. Choose the option that most directly restates the cause-and-effect relationship shown in the experiment.
Hints
Locate the explanation for the recovery
Reread the sentence that begins "Chen attributed this recovery to..." What change in the types of plants within the exclusion plots does she mention?
Focus on what happens without insect pollinators
In the exclusion plots, which kinds of plants decreased, and which kinds increased when pollinators were absent? What does that tell you about which traits are helpful in a pollinator-poor environment?
Check cause and effect
Make sure the choice you pick matches the cause-and-effect pattern: the environment has few pollinators, and over time certain plant species are favored. Which option describes a trait that would clearly work well under those conditions?
Step-by-step Explanation
Identify the goal of Chen’s inference
The question asks what Chen would most likely infer from her observations. That means we must use the experiment’s results and her explanation (attribution) to figure out what general conclusion about plant species she would draw.
Summarize the key results of the experiment
When pollinating insects were excluded from some plots:
- In the first three years, plants in those plots produced about 40% fewer viable seeds than the control plots.
- By year 7, seed production in the exclusion plots had rebounded to equal that of the control plots. This shows that, over time, something changed in the exclusion plots that allowed seed production to recover even without insect pollinators.
Note Chen’s explanation for the recovery
The passage tells us exactly what Chen attributed the recovery to:
- Inside the exclusion plots, there was a marked increase in flowering species that could fertilize their own ovules without insect visitation.
- At the same time, insect-dependent species sharply declined. So in a setting with few or no pollinators, species that need insects do poorly, and species that do not need insects do well and become more common.
Turn the specific observation into a general inference
From this pattern, the logical generalization is: in a pollinator-poor environment, plants with traits that let them reproduce successfully without insect pollinators will be favored over those that depend on insects. Now we must select the answer choice that states exactly this idea.
Match the inference to the correct choice
Choice D says that such an environment will tend to favor plant species that "possess reproductive mechanisms that allow successful fertilization without the aid of insect visitors". This directly restates the trait Chen identified (self-fertilizing without insects) and fits the observed increase of those species and decline of insect-dependent ones, so D is correct.